1. Field of the Invention
The present invention relates to a tire forming mold for vulcanization forming a tire and a tire manufacturing method using the tire forming mold.
2. Description of the Related Art
The tire forming mold mentioned above is constructed by combining a plurality of mold portions, and can be roughly classified into a two-piece type and a segmented type based on the mold structure. The latter type is provided with an annular mold portion 11 forming an outer surface of a tread portion outer surface of a tire, and a pair of side mold portions 12 and 13 forming an outer surface of a side wall portion of the tire, as shown in FIG. 13. The annular mold portion 11 is constructed by a plurality of sectors divided in a tire circumferential direction, and the respective sectors get together so as to form an annular shape at a time of a mold clamping, and displace to an outer side in a tire diametrical direction so as to be away from each other at a time of a mold open.
The annular mold portion 11 is fitted to an outer side in a tire diametrical direction of the side mold portions 12 and 13 at a time of the mold clamping, and comes to a state in which a fitting surface 11a thereof is closely attached to fitting surfaces 12a and 13a of the side mold portions 12 and 13. Accordingly, the tire forming mold is worked at a high precision such that a fitting diameter D11 of the annular mold portion 11 comes to the same dimension as fitting diameters D12 and D13 of the side mold portions 12 and 13. However, if the fitting diameter D11 becomes smaller than the fitting diameters D12 and D13 due to a dispersion of work or the like, a gap is formed between the sectors at a time of the mold clamping, and a rubber burr called as a pinch is generated on a tread surface of the tire. Since this pinch is formed discontinuously on the tread surface, a removing work (a pinch cut work) becomes very complicated.
In the tire forming mold described in FIGS. 5 and 6 of Japanese Unexamined Utility Model Publication No. 63-161806 and Japanese Unexamined Patent Publication No. 2000-108130, an annular pinch is generated between the annular mold portion and the side mold portion by a groove provided in the fitting surface of the side mold portion. However, since the pinch generated thereby is formed as an approximately rectangular cross sectional shape and has a uniform thickness, a cut position with respect to the pinch is not stable particularly in the case of a manual work, which raises a problem that a cross section of a cut trace after the pinch cut is dispersed, and an appearance of the tire is deteriorated.